kids can be better players than adults, they learn fast and tend to be more eager. they dont take things so personally either in my experience.
13 would be a good min age, but would be difficult to enforce. my kids have tried the game, but the ps3 was far more enticing so they didnt stay.
Language i dont really worry about, evony has a basic filter system for chat, and i doubt what can get thru even comes close to school language lol [surely you all remember swearing and insults at school :P]

